The function of this Shared Resource is to provide an efficient, economical and effective use of animals for the performance of cancer-related studies. A significant emphasis is placed on the use of immunocompromised rodents. Major services provided by the Animal Research Resource include: animal purchase requests; inoculation of animals; propagation of tumor cell lines in animals; measurement of tumors; administration of carcinogens, s and hormonal agents; and necropsy. A service for the production of rabbit polyclonal antisera is also provided. Two additional rooms are also maintained to NIH Biosafety Level II standards for investigators using retroviral vectors and chemical carcinogens. Small transgenic breeding colonies are also maintained and a new transgenic Service has been established within the Resource, co-directed by Drs. Clarke and Dickson. The Shared resource is located within the Georgetown University Medical Center Research Resources Facility (RR). The is a centralized, AAALAC accredited and USDA registered research facility. All cell lines for inoculation require evidence of current murine antibody production test status. The general environment and animal health is monitored by the use of sentinel mice maintained in each colony room. All immunocompromised rodents are maintained within a viral antibody free environment. The services of this Resource are critical to the effective and economical use of animals by LCC investigators. The highly trained and experienced technical staff work closely with Cancer Center members to provide quality animal care and technical services in support of peer reviewed projects requiring the use of animals. Continuing increases in demand has required an increase in space to maintain rodents. We anticipate a further 50 percent increase in usage over the next five year period. The space requirements will be met with an ongoing RRF expansion. In 1995, the Shared Resource was utilized by 24 cancer center members m eight programs. 96 % of the projects utilizing the Shared Resource were supported by peer